           1 (add-overlay controller
                          ;; Just one variable, take full cell, using either encoder,
                          ;; suppress the other one.
-                         (let [paired-note (odd? note (dec note) (inc note))]
+                         (let [paired-note (if (odd? note) (dec note) (inc note))]
                            (reify IOverlay
                              (captured-controls [this] #{(control-for-top-encoder-note note)})
                              (captured-notes [this] #{note paired-note})

  [controller note]
  (let [room (room-for-effects controller)
        fx-info @(:active-effects (:show controller))
        fx (:effects fx-info)
        fx-meta (:meta fx-info)
        offset (- 4 room)
        x (quot (- note 20) 2)
        index (- x offset)]

  [controller note]
  (let [room (room-for-effects controller)
        fx-info @(:active-effects (:show controller))
        fx (vec (drop (- (count (:effects fx-info)) room) (:effects fx-info)))
        fx-meta (vec (drop (- (count (:meta fx-info)) room) (:meta fx-info)))
        offset (- 4 room)
        x (quot note 2)
        index (- x offset)
        var-index (rem note 2)]
